Dermatitis herpetiformis (DH) is a chronic pruritic blistering disease characterized by an asymptomatic patchy duodenal jejunal atrophy and the almost universal deposition of IgA at the dermal epidermal junction of the skin. Both gut and skin disease respond to a gluten free diet. This grant proposal is designed to evaluate previous observations made in our laboratories that have demonstrated the presence of serum IgA immune complexes in approximately 40% of DH patients. Our preliminary data indicate these IgA immune complexes contain gluten and gliadin. We plan to examine the relationships among serum IgA immune complexes, IgA skin deposition and the ingestion of wheat using a modification of the Raji cell assay to measure IgA immune complexes. To examine tissue IgA immune complexes, we will employ a suction blister technique which creates small subepidermal blisters at the site of IgA deposition in DH skin. Fluid removed from these blisters will be employed in the Raji cell assay. IgA immune complexes will be isolated from conglutinin beads and characterized employing gel double diffusion, immunoelectrophoresis, SDS PAGE and skin autoradiography. Finally, we plan to examine the specificity of these IgA immune complexes by studying other diseases in which IgA is found at the site of pathology and gastrointestinal disease where damage of the intact mucosal barrier may result in stimulation of the IgA system by ingested antigens.